Machine element



N m so \o un N m n 1 t v N .8,1927. ,E1 ov E. o. BRowER 164844 MACHINE ELEMENT original Filed Aug.1s. 1920 5 Sheets-sheet l Flg Figa.

Ngv. 8, 1927.

5 Smm-Sheet 2 Original Filed Aug. 18, l920 In Venfor Nov. 8, 1927.

1,648,441 E. o. BRowER MACHINE ELEMENT Original Filed Aug. 18. 1920 5 SheetS-Sheet 3 Fig. ,/,0

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E. O. BROWER MACHINE ELEMENT Original Filed Aufl. 18, 1920 5 Sheets-.Sheet 5 /IB //5 Fig 8 /7 //4 //.5 Il) //4 I8 60 Figi la.

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ELBEET o'. 'EinowEag or rrcNfrNeroN, NEW Yoan.

MACHINE ELEMENT.

continuation of application serial iva-404,286, filed August is, 1920. This application inea December as,

1922. Serial No. 609,503.

This application is a Continuation ofapplication Serial No. 404,286, filed August-18, 1920.

My invention relate'sto means forfaciltating precise control -of 'the relative position andmovement of two bodies which are not fastened permanently together, especially in circumstances where thev motionsl are' slow or intermittent and the bodies are p'onderous and massive; In a ,OfeneralA sense', the movable body is rendered free for its normal motion by relief of friction, while motions in abnormal directions are prevented by supporting surfaces Vwhich may be in very close contact over relatively large areasi An object of the invention is to furnish necha'nism for various commercial purposes which will secure a moderate degree of prezcision with less painstaking labor than is n'ow required of a machine operator. Another object of the invention .is to produce mechanism which will function with a high degree .of precision, with relatively little exercise of skill and patience by the operator. Another object is to produce mechanism for scientific or other uses which will afford the utmost attainable precision, in the space relations between two bodies, which is compatible with great facility in changing such spacev relations quantitatively. Still another object is to produce a machine which will indefinitely maintain the desired relationship of its movable partsvwhe'n these have been set, without danger of displaceinent by vibration or accidental disturbances.

Still another object is to enable the movable or traveling member of a machine to be moved readily thru a very small distance without the hindrance usually resulting from the inertia of starting friction. StillV another object is to render the movable member perfectly amenable to control, withy respect to position and motion, while-it is being moved continuously or intermittently at an extremely slow rate of speed.v Still other objects and advantages will be apparent as mv disclosure is examined.

To `jive a. preliminary understanding of.

the invention: Tt is known thatrit requires more force to start a traveling carriage 'or other movable body Jfrom 'rest' than it'does to maintain the motionv after the body hasv started to slide. This phenomenon is coni,-

monlyI known as vstarting friction orv as the inertia of starting friction, and where precise results are required it frequently produces inaccurate andV uncertain response of the movable element to its controlling means, especially inV cases where a very slight adjustment or change of position is required;

This imperfection of response is probably due to several causes,`one of which is lno doubt the minute changepof configuration of the parts, or strain, 'due to stresses. engendered in overcoming friction between theV carriage and its supports.` In' carrying Out my invention I avoidvv starting .friction by i interposing a -constantly moving part between the movable element and the element on which it isto be supported.` Y When the'v carriage of an ordinary machinefissliding with a moderatevvelocity upon its stationary supports, there is no adhesion of restl because the carriage is notl at rest; but in my nicchanism.r whether the carriage is moving or still, there can be no adhesion of rest'because the supporting .surfaces are not at rest. lVhe'n the ordinary mach-ine carriage is moving, there is more or less' frictional opposition or resistance to that motion; but my invention can 'be so embodiedjth'at this Vvfriction of travel is diminished very materially, and in certain circumstances substantially ifnotabsolutely abolished. This diminution of kinetic 'friction will bel illustrated after certain of the embodiments have been examined. `Wh`ere ample stability is principles which I d'isclose herein, ponderous bodv 'may be maintainedin certain' iles'pects as immovable as if it tiene flirled tov its foundations, while at the same time it is' rendered as free to move in certain ways as a mass .suspended by a longvcordis vfree to swing horizontally; and to employ another `figurative illustration-as a 'drop vof rain assumes a symmetrical forinin the air, and

tends constantly to preserve this perfect .symmetry against the vicissitudes of its journey to the earth, somewhat similarly, the carriage of my mechanism is permitted to balance and ad]ust itself, on account of the constant motion of the supporting surfaces, while anyY accidental strainsr and stresses tend to be dissapated and absorbed.

. Thepprinciple of the invention is illustrated in the accompanying drawings in threeiforms,-Figures l'to @inclusive illustratingv one form, Figures 'T'to 11 av second Y form, and Figures 12 to 18 a third form.

@the section .Figure-1 is a longitudinal sectional elevation of mechanism embodying the invention, being taken on the line 1 1, Fig-J4; f

Y, AFigy2 is a sectional elevation on the line ..Fig.' 3 is a top plan view of the parts shownin Figures 1 and 2,; but with the movable element or carriage removed forreveal- .ing g the parts beneath Fig. i is a cross sectional elevation taken on 'the line H, F ig. 3;

which the motionV ofthe carriage is rectilin- K ear, the normal carriage motion being controlled by a feed screw.

Fig.' 7Vis'a side elevation of ay form inV 'which/(he carriage motion is rectilinear, and

inv which the carriage is held against travel alongits normal pathV by spacing blocks at' gone end abutting lugs on the support and at the other end abutting lugs on the carriage.

Fig. 8 vis a longitudinal sectional elevation 'of' the form shown in Fig. 7, the section being taken von the line 8 8, Fig.4 9 ;V

V Fig. 9 is a top plan Vviewof the mechanism of `YFig with the'carriage removed;

V v-lFigf 10 is atransverse sectional view o theline 10-10, Fig. 9; V

F-ig. 11 ris a 'transverse sectional view on the line 1f1--11, Fig. 9.

v The next seveniigures.illustrate a forni of embodiment in which'the path of the carrriage is circular and of large radius, Jthe carriage-being'held either by spacing'blccks or by4 adjusting screws; this form `being 'operative when constructed for a' 1bathv of any specific large radius up to infinity.

Fig. 12 is a top plan view with parts of the 'carriage' broken away. V

Fig. lis a cross section, showing in elebest shown in Figures 1 to 3.

vation a few features` only, the sectie-n being taken on the line 13-13, Fig. 12. Y

Fig. 14- is a fragmentary longitudinalV seetion on the lines lei-14, Figures 12 and 13.

V Fig. 15 is a crosssectioii on the line 1,5445,

circular. The curvature of the carriage'path is magnified in these two views as it would not otherwise befapparent.

'Fig 18 is across sectional diagram of the carriage showing geometrical and numerical relations between the curvature of theVcarriage path and the curvature ofthe supporting surfaces. l

V Fig. 19 is a sketch in perspective to illustrate a physical demonstration of a'certain principle or law of friction. V

Like numerals denote likeparts thruont the several views. 'i

Referring first to the formA shown in Fig` ures 1 to 6 inclusive: V

The element 1 inay-be regarded as typical of the stationary bed or frameworlrof a ina` chine tool. It has two longitudinal half bearings 2 for supporting the cylindrical, continuously rotating elements 3. For the sake of lubrication it is desirable to form lateral depressions t in the bed alongside of the bearings for containing'oil for lubrieating the elements .3 which for convenience' will be referred toas` cylinders. The oil grooves L1 are closed at the ends bydams 6 which are simply plates screwed onto the bed opposite the ends of the grooves. It is desiraway at the. center, as 'at 8, Fig. 5,'in order 'that the effects of wear may be somewhat direction transverse to the cylinders. The

bearing at the left, Figures i and 5, is

grooved at the center as at12, like the bearings of the base.

Said cylinders 3 are held against longitu` dinal ldisplacement by feathersor keys 14, vThese are iabbeted into the bed 1 and project up into annular grooves 1G formed in the cylinders. The cylinders arerotated by means'of iiitegral gears '1S meshing with and driven by vworms 2O rigidly secured to a transverse shaft 22 driven by a pulley '2li or other appropriate means. V

While it is not always essentialV that ineand at the same time be guided able that the bottoms of the grooves be cut` 'charnica'l'means be provided for shifting the carriage longitudinally upon the rotating cylinders, it is nevertheless desirableA to do so in certain cases, and in the forni shown in Figuresrl Ato 6 I have illustrated al feed screw 28 whch lies parallel to andbetween the cylinders' and occupies a position in a longitudinal chamber 30 formed in the top of the bed. For rotating this screw, I have shown a. hand wheel 32 having a graduated scaleli on its periphery adapted to cooperate with a pointer 86. This' pointer is shown fixed; but it will be understood that the pointer may beniovably mounted, and

vshiftable by hand or otherwise so as to coin- ,peiisate for minute errors in the feed'screw;

also a` vernier' may be preferable to a. mere pointer in certain cases, but vei'niers are knowii it need not be here illustrated in detail. The screw is prevented from moving 'longitudinf'illy by a bracket 38 having a lug 404 projecting intor `'the groove of a grooved `collar 42 rigidly fastened to the shaft, as

best shown at the left end of Fig. 2. In order to keep the collar seated on the lug, I have provided a spring holder illustrated in some detailY in Fig; 6. According tofthis vdesign a saddle 46 rides upon the periphery of the Acollar and is held down by springs 48.

As a result ofthis construction, not only is the grooved colla-r held firmly down seated vupon thelug, but the device constitutes a take-up for automatically adjusting the parts and keeping theniin close bearing in case of` wear.-

The connecting means betweenthe feed `screw and the carriage is best shown in Figures 2 and 5. A stationary half nut 5() is bolted to the under side of the carriage and passes to the'under side ofthe screw where it has internal 'threads adapted `to receive and cooperate with the threads of the screw. In order to assure' the firm vand continued seating'of the screw in the half nut, a pressure member 52 overlie's the screw a-i'i'd" is constantly urged down'upon'it by means of helical compressionl springs 54 seating in sockets 56 formed in the underV siide of the table. j l

The rotary movement of the cylinders permits the carriage to rnove so easily that mi? i'ifutc adjustn'ients n'iay be readily andv'accu- 'rately made, for after the handwl'ieel has been' turned to a particular position, the inoti'on of the cylinders enables the carriage by itself to make a' minute and final adjustment under the' reactive forces 'arising from the resilience of the parts'and the minute dis'-v `toi-tion resulting from'- the change ofthe liandwheel. The stresses and strains generated by the force necessary to shift the carriage promptly become dissipated, and the parts assume their normal and proper configuration. It will ibeunderstood, of course,

that'the' distortion in` the ordinary machine tool', occasioned by av` shift ofthe carriage,

may not'be visible tothe eye, butin precision Yworkit may bel readily demoiistrate'dlthat distortion exists. In the,y forni shown in Figures 1 to 6 the carriage is shifted or fed by means of the hand wheel 32 andv tlre' screw 2'8 after the ,fashionv of ordinary vfeed or lead screws; but as friction is relieved by the roftating cylinders, thel scale readings oi'ithe hand wheel may be relied upon toa degree not attained 4in present machines; and

if the screw 28 is rotating continuously for a longtime or intern'iitteiitly, and whether itsV rate of motion isA increasing or d'ecreasl ing 'or remains Auniforin,it will be rinden stood that a precise'correspondence Abetween the carriage and' itsvcontrolling screw will not be disturbed by reason of any ertrein'ity `of slowness in the rate of carriage travel while the cylinders are in operation. i

n Theform sliownin Figures 7 to 11is siiiivilalto the one already described, except that in this case there is no provisionz for mechanical control of carriage motion. The carriage is shifted froinrone place to another by hand, and then held ragainst travel by accurately formed blocks-or gages 60 which at one end engage lugs 62 rising from the bed, and at the other endkv engage lug `(i4 depending f-roin the bottom of the table.

In the type shown in Figures' 12 to 18,".tlile j norinal path of they carriage is circular and friction is relieved bythe rotation of a number of individual elements which forconvenience will be referred toas dis-ks.' The disks are arranged in three rows. In one row are the disks 70v so mounted and adjusted that their upper sides, which are flat, are all at the saine height or level to support the carr'iage Aby contactlwith the rail 73. In another row are the disks 90. mounted' at an inclina.-

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tion from the horizontal, with their upper sides which ai'e conv-exly spherical adjusted to support the rail 91. In therthi'rd row arc the disks 92, mounted at an inclination opposite to that of the second row, with upper si'deswliich are concavely spherical for'supporting the rail 93. The curvatures of these "disk surfaces are too slight to be apparent in the drawing without an objectionable exaggeration.. rows of disks form a lVas shown; in Fig. 13,

Taken together, the last twol andas may be noticed iiiFig. 12. The purpose of this V is to enable-the 'disks to prevent the carriage from moving* transversely ofthe wedges 74 is exaggerated in order to and it will make it apparent in the drawing be understood that the rail 72 is machined well enoughL so that no coarse adjustments need be made 7by `wedges 74.l The disks 70 are` relieved. or cut away slightly so that the vrail can have no contact near the c-entcrof the disks; and besides this clearance in the disks, the width of the raily 73 is made considerably narrower than the diameter of the disks, as shown in Figures 12 and 13; 1n

consequence, the directions of motion of the disk surfaces are nearly or quite at right V angles'to `the carriage path when they'are vin. contact with the rail. The disks turn about pins 71 which are secured in the blocksv 72gwhich aremaintained in proper adjustment upon their inclined seats in the base 99 byadjusting screws in the plate 7 6 which is fastened to the side of the base. The lower surfaces ofthe blocks 72 are cylindricalin form, thus enabling the blocks to Vbal- -ance 4the disks under their loads, and serving other endsl which need not be reciteda The disks 70 are kept inimotion Yby peripheral teethA whichV mesh in the screw or worm thread ofthe segments which are articulated to form a'bent shaft which follows the curve of the row of disks 70. As this curv-e is of krelativelyf large radius, the angle -between adjacent segments 80 is a small angle, and hence a faultless universal joint is not lneeded lto allow one segment to drive its neighbor-instead acrude tongue and slot, as `indicated-at 83, Fig-.112. may be quite tol- The segments vmay be held against in-;annular grooves and serving also to hold the segments down in place, as indicated at V88, Fig. 12. Gn one of the segments 80 are provided helical teeth Y81li`igures 12 and 15, meshing with and driven by ahehcal gear Y84,`Fig. 15, on the transverse shaft 85 which i is driven byia pulley 86 or other suitable means. s On shaft 85 is another gear 84 meshing with and driving teeth 81.0n a segment of a second articulated shaft 82 whichdrives both rows of inclined disks asis apparent in Figuresy 13 and 12. The inclined disks 490 and 92 are mounted on taper blocks 72 which are held in place Vby, adjusting screws in individual plates 98 and97 which are bolted l to the base 99. The rails`91 and 93 are adjustably secured to the tablelike the rail 7 3. These rails can obviously be mounted in sections when'warranted by conditions of temperature expansionror other reasons.

Qln Fig. k12, 102 is a graduated'scale fixed tothe carriage, and 103 isa vernier mounted Von the base and adapted to indicate the position rof the carriage while .the same is held `against travel. by lug 107 on the carriage which is gripped between two screws 108 car-` ried in posts 109 which are adapted to b-e set j lin any ofthe holes 110 in the base 99, Figures 12 and 13. Y

In Fig. 12, 111 is a 99 and trasversely located so as to pass ,between the legs of elements 114, Figures 13, 16 and 17, which for convenience will be relug iXed to `the basev Y Y ferred to as benches.) SeveralV of these Y benches 114 are mounted in Va row under one side of the carriage, of which three are represented ,in the side elevation Fig. 16, and

soVV

the bottom plan View Fig. 17.. A simple bar- Y I 115 seats properly on the insideoftwo legs of a bench and bridges the gap between themY to makevr an abutment j for one end of the Johansson Blocks or gages` 60, which at their Y other end seat upon the hemisphere 'i118 whose convex surface tits properly in a concave recess or depression in the lug 111 fixed to they base 99; and a like aggregate of measuring elements is provided and disposed oppositely to the first in order to hold .the carria'ge at a specific position of itspath. The elements 118 have a spherical form instead of a cylindrical one in orderto permit the hemisphere with its adjacent gages 60 to be grasped and turned between its abutments at-any time without disturbing an adjustment of the carriage, for the purpose of insuring a proper contact at the abutting surfaces. It will be understood that the gages 60 are finished, and the working surfaces of theelements 114,115 and 118 should be 4tinished, so perfectly that they will adhere to each other on simple contact with a cohesion amply sufficient to support Y.their mere weight; but when there may be a suspicion that the measuring elements have .become slightly 'displacedby accidentV or lexcessive vibration, it is important to be ableto'insure a proper contact by the manipulations men-v tioned. It will be clear that whatever position the carriage may occupy, it `will be `pos- Y sible to establish connections Vbetween the lug 111 and two of the benches but some numericalconsiderations remain to be examined. In order to simplify this phase of the its ownxbar, and one side of a bar will be precisely in the middle ofthe lbench slot whichever way it is used; in otherv wordstlfie bench and-'barjafl'rord a concrete basis for making a physical measurement in either d1- rection from an imaginary line and plane through the middle of the bench and the.

center of rotary motion of the carriage. 'l l 1e lug 111 has the centers of both its concavities `located ,at some, definite distance from Vthe A center of carriage motion, and this radius should be made some even number of inches,

since the gages 60 are made in inches and decimals of an inch. Then in any particular instance, the length'of an aggregate of Ablocks 60: divided by the radius at which the lug 111 is located is numerically the sine of ,the :angle between the bench slot center andthe centerlof ythe recess in lug 111. If the cen ters of the two concavities oflug 111 are separated by an even number of degrees of angle, and the benches are spaced iat even degrees, it will be Clear that the problem ,0f

determining the PQStOIl 0f the Calflege from the particular blocks in .use,and the problem of ,determiningwhat different `aggregates of gages need be used to bring the carriageto some lother specific position, can he readily handled by the' skilled workman who is familiar with the .toolcommonly known asa sine bar.

The. diagram of Fig. 18 is intended to show certain Vrelations which must obtain in any specinc case between the radius of curvature of the path of the carriage, vand .the

radii l,of curvature of .the guiding'surfaces. 11n this flgure, line 125 represents the center of .motion graxis of rotation of the carriage; line 127 coincides with line 127, Fig.

v13, which .represents the axis of rotation of the d-iskQO.; and line 129, Figures 18 and 13, represents 4the axis of rotation of the Ydisk 92, Fig. 13. The line V125 is evidently lined in vrelation to the base `9,9, the radius of the lpath .of Athe carriage `being known;

andthe lines-12T and 129. are substantially .liked in relation to the base, since the move- .ments of kthe disks during adjustment may be neglected in this relation. Hence the lines .125 and 127 intersect at some knewn point 128 1'8, which is the center of curvature of theA .upper surface of vdisk 9,0, Fig. 13.

Likewise the upper concave side of-disk 92,

1 3, has a .radiuswhich ,numerically the distance from. the curved .surface of the rail V 93, Fig. 13, to the point 130,

Fig. 18,.where lines 125 "and 129 intersect;-

and the rail 93 thisy same vradius of curvature, of course, notmerely laterally, but also longitudinally. Similarly, the entire VJ curved working surface of rail 91, .When'it is in perfect adjustment, is a 'portion' of a spherical surface having its center at point 128. The axis of rotation of disk 7() is parallel to line 125, hence these have no finite intersection andI the curvature of disk is infinitefthat is, they disk is `flat. It will be understood that this type of embodiment vcan A The inclination of so that ijf the button is pushed down the slope for a way. the button Willnotconbe constructed withthe center of motion of the carriage (as line 1,25)` at any inclina'f tion; but with the anis vertical asherein illustrated,` the carriage'wwill notatend to move in its path of its ownl weight.

j .For controlling the carriage precisely while it. is ininotion, there can be provided 1 a worm and worin gear; but' these gears are rwell known "and l need not illustrate .their application to this embodiment. s Whatever means may' be used for .controlling'the carriage motion or position in this type of embodiment, it will be clear thatthe l a slightinclination by some convenient objectl placed inside the book. 135 is a rpiec'e of cardboard, bent over so that'itcan vhe easily vguided by .hand alongthe edge1 36" Of the cover. A thread 137 is passedthrough jthe'caifdb'oard to a button 138 orsome Qon- .venient object to which the -threadcan be easily secured.

the i book cover is, .set

tinue to'slide ofitself; orinother words,

the book cover is inclned'frornthe horiaQntal 1at some angle whose 'tangentV is less than the coefiicientfof friction'of slidingrcontact.

4The button is then placed as atf139`and lthe cardboard is slid along ythe book'edge, Ydragging the button to anew position 140. If the location V139 istaken not-too far from ,the edge 136, it will be found that the butilm desc-ends the Slope @1S it is dragged l10n-g;

.thoug'hnot beyond a certa-in definite lmitwhichvaries ifthe inclination .ef .the -slope is varied. l N ow while the button is at rest onthe book cover, there is a force tending toslidethe button down the slope (this force being the sine of .the slope angle multiplied by `the weight of the button) but opposed to this ferce is the frictionof contact with the book which` prevents -the button from sliding down. Hence, in order that the button may slide, either the force must be increased until it can overcome the friction, or the friction must be diminished enough so that it ,cannot prevail against the force; But :it is 4plain the tension ofthe thread cannot increase .the force, instead lit tendsfslight-v .to oppose tl e force. Thereforetheifricx A tien hasbeen diminished; or in other words, 1t is demenstrated that the sliding Contact 1n one direction diminishes frictional yopposition l to simultaneous motion in transverse directions. l .Y

to retard the carriage. Even if these tend-` encies neutralized eachother in theory, vthey Y would not beflikely to do so perfectly in practice; 'but by making the` rail narrow,

as'shown inthe drawing, these tendencies "are" evidentlyv very much reduced in quantity',` and doubtless the neutralization is more Ynearly complete with a narrow rail so l.that the carriage is substantially free from Yany positive Vtendency to travel iiidu'cedbyfrictionwith the disks.; Hence it is clear that a motion of the supporting surfacesv at right angles to the carriage path is L.the ideal forni of support when it is de- 'Sirednotinerelyto avoid adhesion of rest but also to reduce the friction of vcarriage travel; such motion at right angles avoiding adhesion of rest because itis 'continuous motion,f`an'd avoiding l,positive influence on carriage travel as mentioned above, and functioning positively to diminish kinetic y *friction ofthe carriage as was shown by the experimental demonstration of Fig. 19.

A; very common 'means of facilitating thel Vcont-rol of motion rvis the ball bearing, and one ofitsappropriate applications is in the carriage v,of the typewriter where vit permits vthe carriage to respond properly to the control of thelescapement: Neither the weight of the carriage noi' the impact of the type barscan deforni the bearing balls'froin the 'spherical enough to become apparent in the printing of the machine.v In contrast to this application, if balLbearingswere used for the. carriage-ofa heavy grinding `machine, fora carriage which carried a` heavy grindin'g wheel rotating at high speed, the bearing balls'might bey deformedenough to 'render impossible that Anice precision which a grinding wheel is `able to produce when it is mounted and moved with adequate rigidity, and stabilityf Thus my invention may be compared to 4the Aball bearing as a means for facilitating (relatively slow) motion,

l randcontrasted to lthe ball bearing in regard to fstability.-

Though Ihave emphasized the application of my invention to mechanism having bearing surfaces of relatively large area, I do not restrict it to such bearings; for clearly' the principle or law. of friction exhibited l in the experiment of Fig. l9'is validV for point contact, so called, in a bearing.

Also, it will be realized that if an embodiment of my invention were used without any lubricant, the mechanism would still `riage provided with rbearings for overlying be operative -so far asV diminution tional inertia is concerned. l f Havingv thus described my invention, what I `claim as new and desire to secure by Letters Patent, is:

l. A machine tool having fa supportingV frame, a carriage, and an intermediate ele-V inentfor supporting `the carriage upon the frame, said adapted to have an independent movement non-coincident with the direction of travel ofthe carriage on the'fraine and sliding with respect tocontact between Vthe carriageL lund the intermediate element. A i

T2. A1 machine tool-having a supporting frame, a carriage, 4an intermediater element for supporting the Ycarriage upon the frame, and meansfor continuously inoving'said'intermediate element relativelyV to the carriage for eliminating adhesion of rest betweenthe f of fricintermediate element being f carriage and the intermediate element and reducingthe kinetic friction. Y y

3. A machine tool having a supporting frame, a carriage, an intermediate -cylindrif -al element for supporting the carriage upon the frame, said intermediate element being arranged parallel with the direction of travel of the carriage, and-means for continuously "rotating the cylindrical elerpent ricabout its axis for reducing the rstarting ion and the friction of travel. A s

4. Mechanism'of vthe class described :having a supporting frame, a traveling member, two non-traveling members interposed between the frame and the travelingmember, and adapted to support the traveling meinber andA also .prevent it from Amoving transversely, and means for continuously moving said non-traveling members. K 5. Mechanism of the class-described having a supporting frame, a traveling ineinber, two parallel'non-traveling members interposed between the frame and the traveling memberand adapted to guide the same and carry the weight'thereof, a single power device, and 'connections between said power device and said non-traveling members whereby the latter are moved continuously and in synchronism with each other.`

' y6.. Mechanism of the vclass described hav-1Z ing'a supporting frame, a carriage, parallel cylinders embedded partially in `the'frame and partially inthe carriage whereby movement of the4 carriage transverse to the cylt inders is prevented, a feed screw for advancing the carriage lengthwise of the cylinders,` and gears for rotating thefcylinders for eliminating adhesion of the carriage to the supporting parts andA diminishingv fricl tional opposition to an advance ofthe carriage. f'

7. Mechanism of the class described vhaving rotatable cylinders, a supporting frame` having bearings for said cylinders, a car-` the cylinders, the supporting frame having depressions arranged alongside of the cylinder bearings for containing lubricant,k

means for rotating said cylinders, and means for holding the carriage against movement lengthwise of the cylinders. V

8. A machine tool having a supporting frame7 a carriage, an intermediate element for supporting the carriage upon the frame7 said intermediate element being adapted to have an independent movement non-coincident with the direction 'of travel of the carriage on the frame and sliding with respect to contact between the carriage and the intermediate element, a feed screw7 a nut on y the carriage for causing it to travel when the feed screw is rotated, and means on the supporting fra-me for permitting the feed screw to rotate and preventing it from'y mov- 'i ing longitudinally.

9. A machine tool having a supporting frame, a carriage, an intermediate element for supporting the carriage upon the frame7 said intermediate element beingl adapted to have an independent movement non-coinci-l dent with the direction of travel of the carriage on the frame and sliding with respect to contact between the carriage and the intermediate element7 a feed screw, a nut on fitting parts in engagement with each other. v.

l0. A machine tool having a supporting frame, a carriage, an intermediate l'element for supporting the carriage upon the frame, said intermediate element being adapted to Vhave an independent movement non-coincident with the direction of travel of the c arriage on the frame andsliding with respect to contact between the carriage and the in` termediate element7 a feed screw, a-half nut mounted on the carriage for engaging the feed screw to cause the `carriage to travel when the screw rota-tes, a pressure member mounted on the carriage and spring-pressed i into engagement with` the screw to hold the latter in close contact with the half nut,

and means vfor permitting ther feed screw to rotate and prevent it from moving longitudinally. Y

Signed by me this twenty-seventh day of December, 1922.

' ELBERT O. BROWER. 

